Serial printers or line printers are printers that print one character at a time within a line. They are inexpensive to manufacture, reliable to operate and compact in size, so that they are suitable as tabletop devices.
Printers of this kind are widely employed as type printers, dot-matrix printers or ink-jet printers. When photocurable ink is used in ink-jet printers, then, aside from the printing head, there is a need for an exposure head that runs on a carriage and that, after the printing, exposes the printed image to high-intensity radiation, thus curing it.
For purposes of attaining high radiation intensities, it is a known procedure for sheet-fed offset printing machines to make use of exposure heads with mercury-vapor lamps that reach temperatures of about 900° C. [1652° F.] during operation. Such exposure heads, however, are not suitable for use in tabletop devices because of their large dimensions and the high electric power that has to be installed. The dissipation of the amount of heat generated, which often lies within the kilowatt range, would pose insurmountable difficulties for tabletop devices. In some cases, sheet-fed offset printing machines employ liquid-cooled exposure heads that require cooling aggregates whose dimensions alone already far surpass those of a tabletop device.
The use of exposure heads is also known for large-scale plotters that employ several printing heads on a carriage to simultaneously create several lines of a printed image. These exposure heads are air-cooled and, owing to their large dimensions and their high electric power loss, are not suitable for tabletop devices. Their powerful fans produce noise that far exceeds the permissible noise level in tabletop devices for office applications. This noise reaches the surroundings directly without being muffled since the large-scale plotters are not equipped with a housing. If a housing is installed, the risk exists that the heat energy might accumulate in the housing and cause thermal damage. Moreover, the exposure heads with the reflectors they employ to direct the radiation are not effective to meet the requirements of a serial printer since they make use of elongated, tube-like lamps.